Evaluation of ETV6/RUNX1 Fusion and Additional Abnormalities Involving ETV6 and/or RUNX1 Genes Using FISH Technique in Patients with Childhood Acute Lymphoblastic Leukemia.

Abstract

Childhood acute lymphoblastic leukemia (ALL) is the most common type of childhood leukemia. Specifically, ALL is a malignant disorder of the lymphoid progenitor cells, with a peak incidence among children aged 2-5years. The t(12;21)(p13;q22) translocation occurs in 25% of childhood B cell precursor ALL. In this study, bone marrow samples were obtained from 165 patients with childhood ALL. We analyzed the t(12;21) translocation and other related abnormalities using the fluorescent in situ hybridization (FISH) technique with the ETV6(TEL)/RUNX1(AML1) ES dual color translocation probe. Conventional cytogenetic analyses were also performed. ETV6 and RUNX1 related chromosomal abnormalities were found in 42 (25.5%) of the 165 patients with childhood ALL. Among these 42 patients, structural changes were detected in 33 (78.6%) and numerical abnormalities in 9 (21.4%). The frequency of FISH abnormalities in pediatric ALL cases were as follows: 8.5% for t(12;21)(p13;q22) ETV6/RUNX1 fusion, 6.0% for RUNX1 amplification, 3.0% for tetrasomy/trisomy 21, 1.8% for ETV6 deletion, 1.21% for ETV6 deletion with RUNX1 amplification, 1.21% for ETV6 amplification with RUNX1 amplification, 0.6% for polyploidy, 0.6% for RUNX1 deletion, and 0.6% for diminished ETV6 signal. The most common structural abnormality was the t(12;21) translocation, followed by RUNX1 amplification and ETV6 deletion, while the most commonly observed numerical abnormality was trisomy 21.